The present invention relates to epitaxially grown semiconductor devices and more particularly to a novel method for the independent control of a plurality of volatile dopants in a semiconductor device fabricated by liquid phase epitaxy.
Semiconductor devices, such as red light-emitting-diodes (LEDs) and the like, will operate with very high relative quantum efficiency, i.e., the ratio of emitted photons per unit time to the numer of electrons flowing through the device in the same time interval, only if the semiconductor material is activated with a specific concentration of at least one dopant. Thus, it is known that a LED utilizing p-type gallium phosphide (GaP) and having a lattice doped with a pair of zinc and oxygen (Zn-O) atoms to form luminescent-recombination centers therein, will operate with a very high quantum efficiency only if a delicate balance is maintained between Zn-O pairs and the amount of excess zinc and/or oxygen in the p-type GaP materal. It is desired to derive a method for independent, accurate and reproducible control of these volatile dopants in a liquid phase epitaxy (LPE) system compatible with high volume semiconductor device manufacturing.